Tympanic membrane pressure equalization tube

ABSTRACT

The invention is a tympanic membrane pressure equalization tube. The tube has a distal end and a proximal end and a tube lumen. A medial flange is located at the distal end of the tube and has 2 or more retention elements and a space between each retention element. A lateral flange is located at the proximal end of the tube. The outside diameter of the medial flange is greater than the outside diameter of the lateral flange and the diameter of the medial flange is between about 2.0 and 5.0 mm and the diameter of the lateral flange is between about 1.75 mm and 4.0 mm.

This application is a divisional of U.S. patent application Ser. No.13/800,113, entitled “Tympanic Membrane Pressure Equalization Tube”,filed Mar. 3, 2013, which claims priority to U.S. Pat. App. No.61/622,274, filed Apr. 10, 2012, the disclosures of each areincorporated by reference herein.

FIELD OF THE INVENTION

The present invention is generally related to medical devices andapparatus. In particular, the invention provides systems and methods fordelivering a pressure equalization tube to a tympanic membrane of anear.

BACKGROUND OF THE INVENTION

Otitis media is among the most common diagnoses made by pediatricians. Amajority of children may have at least one episode of otitis media(“earache”) prior to their third birthday. Otitis media is often causedby an inability of the eustachian tube to drain fluid from the middleear. Otitis media is often treated with antibiotics.

A significant number of children exhibit recurrent episodes of otitismedia and/or otitis media with effusion. Treatment of these more severecases often involves the placement of a tympanostomy tube through thetympanic membrane to provide adequate drainage of the middle ear andreduce the likelihood of future infections. Tympanostomy tubes providefluid communication between the middle and outer ear (e.g., pressureequalization) and typically fall out spontaneously within about a yearof placement. Tympanostomy tube placement is among the most frequentsurgical procedures performed in the pediatric population. It has beenestimated that more than a million tympanostomy tubes may be placed eachyear, with typical patients being between about 18 months and 7 years ofage at the time of the procedure.

Tympanostomy tube placement is typically performed in an out-patientsurgery setting under general anesthesia. The physician typically firstexamines the external auditory canal and tympanic membrane undermicroscopic visualization through a hand-held conical shaped speculum.The physician then makes an incision in the tympanic membrane (a“myringotomy”), typically using a standard, small profile scalpel whichthe physician advances through the conical speculum. In many cases, thephysician will then place the tympanostomy tube through the tympanicmembrane, typically using a basic tool for holding and advancing thetube into the myringotomy. The physician may then pass a suction devicethrough the tube, into the middle ear, to aspirate fluid/effusion fromthe middle ear.

A wide variety of tympanostomy tubes is commercially available, and astill wider variety of other tubes has been proposed. Systems have alsobeen proposed to both perform the myringotomy and deploy thetympanostomy tube with a single treatment assembly. In recent years,more complex and expensive systems have been proposed for diagnosis ortreatment of the tissues of the ear, including systems using laserenergy for forming a myringotomy, video systems for imaging of the earcanal, and the like. These various proposed alternatives fortympanostomy tubes and tube placement systems have met with varyingdegrees of acceptance. Some proposed alternatives have been overlycomplex, overly expensive and/or ineffective. Thus, to date, standardtubes and tube placement procedures and devices have primarily used.

Improved devices, systems, and methods for delivering pressureequalization tubes to a tympanic membrane without requiring multipledevices and operator-performed steps can be found in U.S. PatentPublication No. 2011/0015645 which is incorporated by reference hereinin its entirety. A system for automatically puncturing and delivering atympanic membrane equalization tube (i.e., tympanostomy tube) isdescribed. The system can be used to deliver a wide variety of pressureequalization tubes to the tympanic membrane. The current invention isdirected to one such tube, which has been specifically designed toremain in the tympanic membrane for a prolonged period of time.

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings, in which like numerals indicate like elements.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a specifically designed pressureequalization tube that can be delivered to the tympanic membrane.

In one embodiment, a tympanic membrane pressure equalization tubecomprises a tubular body with a distal end and a proximal end and alumen therebetween, a medial flange located at the distal end of thetube, where the medial flange comprises 3 retention elements and a spacebetween each wing, and a lateral flange that is located at the proximalend of the tube. The outside diameter of the medial flange is greaterthan the outside diameter of the lateral flange and the diameter of themedial flange is between about 2.0 mm and about 5.0 mm and the diameterof the lateral flange is between about 1.75 mm and about 4.0 mm.

In another embodiment, the outside diameter of the medial flange isbetween about 3.0 mm and about 4.0 mm and the outside diameter of thelateral flange is between about 2.0 mm and about 3.0 mm.

In another embodiment, the medial flange retention elements are of equalsize and shape.

In still another embodiment the medial flange retention elements have awidth of between about 0.6 mm and 1.0 mm or of about 0.8 mm.

In a further embodiment, the medial flange retention elements have alength of between about 1.0 mm and 3.0 mm or of between about 1.8 mm and1.9 mm.

In another embodiment, the lateral flange comprises two retentionelements.

In another aspect, the invention is a method for placing a pressureequalization tube within the tympanic membrane of a patient. The methodcomprises providing a pressure equalization tube in an uncompressedstate, the pressure equalization tube having a tubular body with adistal end and a proximal end and a lumen therebetween and that has acompressed state and an uncompressed state. The pressure equalizationtube further comprises a medial flange located at the distal end of thetubular body, the medial flange comprising 3 retention elements and aspace between each retention element, and a lateral flange located atthe proximal end of the tubular body. The outside diameter of the medialflange is greater than the outside diameter of the lateral flange andthe diameter of the medial flange is between about 2.0 and 5.0 mm andthe diameter of the lateral flange is between about 1.75 mm and 4.0 mm.When the tube is in the uncompressed state, the medial flange retentionmembers are aligned perpendicularly to the tube lumen and in thecompressed state the medial flange retention members are alignedlongitudinally to the tube lumen. The method further comprisescompressing the pressure equalization tube into a compressed formwherein the medial flange retention members are longitudinally alignedwith the pressure equalization tube lumen into a pressure equalizationtube delivery device and do not overlap one with the other, advancingthe pressure equalization tube into the tympanic membrane such that themedial flange is located medially of the tympanic membrane and thelateral flange is located laterally of the tympanic membrane and thepressure equalization tube is returned to its uncompressed form.

In one embodiment of the method, the outside diameter of the medialflange is between about 3.0 and about 4.0 mm and the outside diameter ofthe lateral flange is between about 2.0 mm and about 3.0 mm.

In another embodiment of the method, the medial flange retentionelements are of equal size and shape.

In a further embodiment of the method, the medial flange retentionelements have a width of between about 0.6 mm and 1.0 mm.

In still another embodiment of the method, the medial flange retentionelements have a width of about 0.8 mm.

In yet another embodiment of the method, the medial flange retentionelements have a length of between about 1.0 mm and 3.0 mm.

In another embodiment of the method, the medial flange retentionelements have a length of between about 1.8 mm and 1.9 mm.

In a further embodiment of the method, the lateral flange comprises tworetention elements.

In another embodiment of the method, the lateral flange retentionelements are of equal size and shape.

In another aspect, the invention is directed to a tympanic membranepressure equalization tube system comprising a tympanic membranepressure equalization tube and an introducer. The tympanic membranepressure equalization tube comprises a tubular body with a distal endand a proximal end and a lumen therebetween, a medial flange located atthe distal end of the tubular body, said medial flange comprising two ormore retention elements and a space between each retention element. Theintroducer comprises a cylindrical member with an inner surface. Theinner surface has an inner surface circumference. The retention elementsare of equal size and shape and the maximum length of each retentionelement is equal to the inner surface circumference of the introducerdivided by the number of retention elements.

In another embodiment the system comprises three retention elements andin another embodiment, the system comprises a lateral flange located atthe proximal end of the tubular body.

In still another aspect, the invention is directed to a tympanicmembrane pressure equalization tube comprising a tubular body with adistal end and a proximal end and a lumen therebetween, and a helicalcoil surrounding the tubular body. The helical coil comprises multipleraised ribs for retention of the pressure equalization tube in thetympanic membrane.

In a further aspect, the invention is directed to a tympanic membranepressure equalization tube comprising a tubular body with a distal endand a proximal end and a lumen therebetween. The lumen of the tubularbody is lined with artificial cilia to aid the transport and expulsionof effusion from the middle ear.

In another aspect, the invention is directed to a tympanic membranepressure equalization tube comprising a tubular body with a distal endand a proximal end and a lumen therebetween and a structure selectedfrom the group consisting of a vent lumen and a wick that would aid ineffusion removal during deployment of the pressure equalization tube.

In yet another aspect, the invention is directed to a tympanic membranepressure equalization tube comprising a tubular body with a distal endand a proximal end and a lumen therebetween, a medial flange located atthe distal end of the tubular body, the medial flange comprising acutting edge; and a lateral flange located at the proximal end of thetubular body. The tympanic membrane pressure equalization tube is madefrom a shape memory material that is pre-shaped with the cutting edgeclosed and centered on the medial flange and will self-dilate followingdeployment.

For a further understanding of the nature and advantages of theinvention, reference should be made to the following description takenin conjunction with the accompanying figures. However, each of thefigures is provided for the purpose of illustration and description onlyand is not intended to limit the scope of the embodiments of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pressure equalization tube accordingto one embodiment of the invention.

FIG. 2 is a side view of the pressure equalization tube of FIG. 1.

FIG. 3 is a top view of the pressure equalization tube of FIG. 1.

FIG. 4 is a bottom view of the pressure equalization tube of FIG. 1.

FIG. 5 is a perspective view of a pressure equalization tube accordingto a second embodiment of the invention.

FIG. 6 is a side view of the pressure equalization tube of FIG. 5.

FIG. 7 is a side view of the pressure equalization tube of FIG. 5, fromthe opposite side shown in FIG. 6.

FIG. 8 is a top view of the pressure equalization tube of FIG. 5.

FIG. 9 is a bottom view of the pressure equalization tube of FIG. 5.

FIG. 10 is a top view of a pressure equalization tube according tofurther embodiment of the invention.

FIG. 11 is a side view of the pressure equalization tube of FIG. 10.

FIG. 12 is a cross-section view of an introducer useful for introducinga pressure equalization tube according to the invention.

FIG. 13 is a perspective view of a pressure equalization tube accordingto another embodiment of the invention.

FIG. 14 is a side view of a pressure equalization tube according tostill another embodiment of the invention.

FIG. 15 is a perspective view of a pressure equalization tube accordingto a further embodiment of the invention.

FIG. 16 is a perspective view of another pressure equalization tubeembodiment according to the invention.

FIG. 17 is a side view of a pressure equalization tube according toanother embodiment of the invention in its unexpanded state.

FIG. 18 is a side view of the tube of FIG. 17 in its expanded state.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description should be read with reference to thedrawing, in which like elements in different drawings are identicallynumbered. The drawings, which are not necessarily to scale, depictexemplary embodiments for the purpose of explanation only and are notintended to limit the scope of the invention. The detailed descriptionillustrates by way of example, not by way of limitation, the principlesof the invention. This description will clearly enable one skilled inthe art to made and use the invention, and describes severalembodiments, adaptations, variations, alternatives and uses of theinvention, including what is presently believed to be the best mode ofcarrying out the invention.

As used herein, the terms “about” and “approximately” for any numericalvalues or ranges indicate a suitable dimensional tolerance that allowsthe part of collection of components for function for its intendedpurpose as described herein.

The tympanic membrane pressure equalization tube according to theinvention is a grommet like device which is folded and/or compressedwithin the tube, and recovers its shape when delivered into the tympanicmembrane.

Embodiments of the invention are compatible for use with a suite ofmedical devices for visualizing the tympanic membrane, puncturing thetympanic membrane, and anesthetizing the tympanic membrane. Examples ofsuch medical devices are shown in co-assigned U.S. patent applicationSer. No. 11/749,733, the entirety of which is incorporated by reference.Accordingly, aspects of U.S. patent application Ser. No. 11/749,733 maybe integrated, combined, and used in conjunction with the embodimentsdisclosed herein.

FIGS. 1 through 4 show a tympanic membrane pressure equalization tube100, also referred to herein as a pressure equalization tube, a PE tubeor a tympanostomy tube, according to one embodiment of the invention. Inthis embodiment, referring to FIG. 1, the tube 100 is configured as atubular body with asymmetric flanges, a medial flange 102 a lateralflange 104 and a tube lumen 106. The medial flange 102 has a largerdiameter 102 d than the lateral flange 104 diameter 104 d (see FIG. 2).The medial flange 102 has three retention elements of equal size andshape, retention elements 108 a, 108 b and 108 c. As shown in FIG. 3,these retention elements have a width 110 of between about 0.6 mm and1.0 mm, or about 0.80 mm, a length 112 of between about 1.0 mm and 3.0mm, or of between about 1.8 mm and 1.9 mm, or about 1.87 mm and arespaced evenly around the circumference of the tubular body lumen 106,that is, the retention elements are spaced 120° apart. The medial flangeoutside diameter 102 d is between about 2.0 mm and about 5.0 mm orbetween about 3.0 mm and 4.0 mm or about 2.11 mm. The distance from thecenter 114 of the tube lumen 106 to the outer edge 116 of the medialflange 102 is 3.25 mm and from the center 114 of the tube lumen 106 tothe inside edge 118 of the medial flange 102 is 1.65 mm.

Referring now to FIG. 4, a second, lateral flange 104 is smaller thanthe medial flange 102 and is uniform in width with three retentionelements and three notches 120 a, 120 b and 120 c that are spaced 120°apart, with each notch 120 a, 120 b, and 120 c at the same location as,or circumferentially aligned with the spaces between the medial flangeretention elements 108 a, 108 b and 108 c. The distance from the center114 of the tube lumen 106 to the outside edge 122 of the lateral flange104, the outer diameter of the lateral flange is between about 1.75 mmand about 4.0 mm or between about 2.0 mm and 3.0 mm or about 2.11 mm.

FIGS. 5 through 9 show a tympanic membrane pressure equalization tube200 according to a second embodiment of the invention. In thisembodiment, referring to FIG. 5, the pressure equalization tube 200 isconfigured as a tubular body 230 with asymmetric flanges, medial flange202 a lateral flange 204 and a lumen 206. The medial flange 202 has alarger outer diameter 202 d than the lateral flange 204 outer diameter204 d (see FIGS. 6 and 7). The medial flange 202 has three equalretention elements 208 a, 208 b and 208 c. As shown in FIG. 8, theseretention elements have a width 210 of between about 0.6 mm and 1.0 mm,or about 0.80 mm, a length 212 of between about 1.0 mm and 3.0 mm, or ofbetween about 1.8 mm and 1.9 mm, or about 1.87 mm and are spaced evenlyaround the circumference of the tube lumen 206, that is, the wings arespaced 120° apart. The medial flange outside diameter 202 d is betweenabout 2.0 mm and about 5.0 mm or between about 3.0 mm and 4.0 mm orabout 2.11 mm. The distance from the center 214 of the tube lumen 206 tothe outer edge 216 of the medial flange 202 is 3.25 mm and from thecenter 214 of the tube lumen 206 to the inside edge 218 of the medialflange 202 is 1.65 mm.

Referring now to FIG. 9, a second, lateral flange 204 is smaller thanthe medial flange 202 and is uniform in width with two notches 220 a and220 b and spaced 180° apart, with notch 220 a be at the same location asthe spaces between the medial flange wings 208 a and 208 b. The distancefrom the center 214 of the tube lumen 206 to the outside edge 222 of thelateral flange 204, the outer diameter of the lateral flange is betweenabout 1.75 mm and about 4.0 mm or between about 2.0 mm and 3.0 mm orabout 2.11 mm.

The tympanic membrane pressure equalization tube according to theinvention may comprise a shape memory material that can be mechanicallycompressed but can substantially return to an uncompressed state.Examples of materials that can be mechanically deformed but can returnto an uncompressed state when not mechanically stressed include a numberof biocompatible metals such as titanium, silver, tantalum, alloys ofstainless steel, cobalt, chromium, and alumina and polymers or otherpliable elastomeric materials such as polyolefins, polyurethanes,silicone rubber, PEEK, PMMA, and fluoropolymers. The tube 100 is oftenmade of silicone rubber and may have an axial length of between about2.0 mm and about 2.5 mm and in the embodiment shown in FIG. 2 the axiallength is about 2.2 mm. The thickness of each of the lateral 104 flangeand the medial flange 102 is between about 0.25 mm and 0.35 mm or isapproximately 0.30 mm and the flange to flange length 126 of the tube100 is between about 1.0 mm and 2.0 mm or is about 1.6 mm. The tube 100may have an inner diameter of between about 1.0 mm and about 1.5 mm, andin the embodiment shown in FIG. 2, the inner diameter is about 1.1 mmand the outer diameter may be between about 1.5 mm and 2.0 mm and isabout 1.7 mm.

In order to deliver a tympanic membrane equalization tube to thetympanic membrane, the tube may be folded down and compressed into anintroducer for storage until deployment into a patient's tympanicmembrane. For certain tubes, particularly those made of silicone rubber,two undesirable effects may occur when the tube is highly compressed andforced to contact itself. The first is that blocking may occur, that isthe tacky surfaces of the tube may cause the tubes to temporarily selfadhere one to the other. Blocking can deform the shape of a siliconeobject by having its surfaces contact one another, holding the object insomething other than its natural free state. Blocking typically does notpermanently change the shape of the object and the natural stresses inthe object will have a tendency to overcome the blocking surface tensionto restore the object to its original shape. The release may take arelatively long period of time (i.e. greater than 1 second). Further,the tube may become compression set, that is, the natural shape of thetube may be permanently deformed due to stress relief of the material.The stress relief can happen due to high stresses being applied for longperiods of time, changing the natural unstressed shape.

In order to overcome the blocking and compression effects, in oneembodiment of the invention, the retention elements (i.e. 308 a, 308 band 308 c shown in FIG. 10) of the tympanic membrane equalization tubes300 are designed to prevent touching of the edges when it they arefolded down and compressed into the introducer for storage and thereforeto mitigate areas of adhesion that may cause blocking. The relationshipof the retention elements to the introducer 320 is described below.

FIGS. 10 and 11 show a tympanic membrane pressure equalization tube 300according to a further embodiment of the invention, and FIG. 12 showscross-sectional view of an introducer 320 for the tympanic membranepressure equalization tube 300. The introducer has an inside surface324, and outside surface 326 and an inner diameter 322. In thisembodiment, referring to FIG. 10, the tube 300 is configured as atubular body with asymmetric flanges, a medial flange 302 a lateralflange 304 and a tube lumen 306, although tubes without a lateral flangeare also contemplated according to the invention. The medial flange 302has a larger diameter than the lateral flange 304. The medial flange 302has three retention elements of equal size and shape, retention elements308 a, 308 b and 308 c, although according to the invention, the tubemay include two, three, four or more retention elements. As shown inFIG. 10, these retention elements have a length 312 of between about 0.6mm and 1 mm, or about 1 mm such that when the three elements arecollapsed they are smaller than the circumference of the inside surface324 of the introducer 320 (see FIG. 12). In the particular embodimentshown in FIGS. 10 and 11, the thickness 314 of the medial flange 302 is0.305 mm. Accordingly, the length 312 of the retention elements can becalculated as follows (L):

-   -   Compressed collapsed inner diameter of tube 300=A    -   Thickness of Retention Element=B    -   Inner diameter 322 of introducer 320=C    -   Collapsed circumference of tube 300=D    -   A=C−2B    -   D=A*π    -   L=D/3

For the embodiment shown in FIGS. 10 and 11, C=1.55 mm, B=0.305 mm,A=0.94 mm, D=2.95 mm and L=0.98 mm. The maximum length 312 of theretention elements in this instance is 0.98 mm, and the length may bebetween about 0.6 and 1 mm. In this embodiment, the retention elementsare of equal size and shape and the maximum length of each retentionelement is equal to the circumference of the inside surface 324 of theintroducer 320 divided by the number of retention elements.

Another method to reduce retention element adhesion according to theinvention is is to add a coating to the tube. A thin coating (0.25 μm)of parylene or other similar biocompatible coating can be applied toreduce retention element adhesion and ensure near instantaneous openingand rapid tube deployment (i.e. within 1 second).

Another embodiment of a pressure equalization tube according to theinvention is shown in FIG. 13. Rather than flanges at each end of thetube, the pressure equalization tube 400 comprises a helical tube.Surrounding the tubular body lumen 402, on the surface of the pressureequalization tube 400 is a helical coil 404 that is a raised rib wrappedin a helical spiral. The tube 400 is retained in the patient's tympanicmembrane by means of the multiple raised ribs that surround the tube400. In this particular embodiment, the inner diameter of the pressureequalization tube is 1.1 mm or between about 0.8 and 1.4 mm, the outerdiameter is about 2.1 mm or between about 1.8 mm and 2.4 mm, the overalllength of the tube 400 is about 2.2 mm or between about 1.8 and 2.6 mm,and the helical pitch is 0.44 mm or between about 0.35 and 0.55 mm.

The tympanic membrane equalization tubes disclosed herein can includefeatures which help recover a misplaced tympanic membrane equalizationtube. A misplaced tympanic membrane equalization tube located distallyto the tympanic membrane can be especially difficult to remove. Suchfeatures can include tethers attached to any portion of the tympanicmembrane equalization tubes. The tethers can be grasped proximally tothe tympanic membrane and used to pull the misplaced tympanic membraneequalization tube out of the ear.

In general, methods for inserting pressure equalization tubes into thetympanic membrane include both simple, manual methods and morecomplicated, automatic systems for making an incision and placing thetube into the incision. A manual method for inserting a pressureequaliziation tube into a tympanic membrane includes placing a speculuminto the ear canal in apposition with the tympanic membrane in order tomore clearly visualize the membrane. Following visualization of thetympanic membrane, a myringotomy blade is inserted into the speculum anda small incision is created in the tympanic membrane (a myringotomy) torelieve pressure caused by the excessive buildup of fluid due toinfection in the middle ear. Forceps are then used to collapse thepressure equalization tube and insert it into the incision to allowexternal ventilation of the middle ear for an extended period of time.Suction may be applied before or after tube insertion in order to removethe fluid in the middle ear.

Rather than applying suction after tube insertion, according to theembodiments shown in FIGS. 14, 15 and 16 effusion removal systems areincorporated with the pressure equalization tube. The pressureequalization tube 500 shown in FIG. 14 has an open lumen 502 lined withartificial cilia 504 to aid the transport and expulsion of effusion fromthe middle ear. The artificial cilia may include microtubules andmolecular motors that create waves or beating action to transport theeffusion or other bodily fluids through the lumen 502 of the tube 500.Such cilia are described in detail in Sanchez, Timothy et al; Cilia-likeBeating of Active Microtubule Bundles; Science 22 Jul. 2011; Vol. 333no. 6041 pp. 456-459, or U.S. Pat. No. 6,849,910 which describes asimilar mechanism for surface fluid transport using oscillatory MEMs.Both publications are incorporated by reference herein in theirentirety.

FIG. 15 shows a pressure equalization tube 600 with a vent lumen 602 andFIG. 16 shown a pressure equalization tube 620 with a wick 622 thatwould aid in effusion removal during deployment of the pressureequalization tubes by allowing effusion to be vented or wicked from theear canal. Further, in the event that the physician desires to usesuction to remove the effusion, an air return path is provided, breakingthe effect of vacuum in a closed space.

Systems for automatically puncturing and delivering the tympanicmembrane pressure equalization tubes into a tympanic membrane aredescribed in U.S. Patent Publication No. 2011/0015645, which isincorporated herein in its entirety and in U.S. Patent Publication No.2009/0209972. These methods generally include grasping a housing with adedicated handgrip, or a graspable housing. A shaft extends out of thehousing to access the tympanic membrane, and the method includes loadinga tympanic membrane equalization tube within the tip of the shaftresulting in a compressed tympanic membrane equalization tube. The tipof the shaft of the graspable housing is then brought into contact withthe tympanic membrane. An internal spring loaded cam-based mechanism islocated within the housing and coupled to a button. The method furtherincludes triggering a mechanism which results in puncturing the tympanicmembrane. Following puncturing the tympanic membrane, the methodinvolves delivering the tympanic membrane pressure equalization tube.The tympanic membrane pressure equalization tube that has been folded orcompressed within the tube and recovers its shape into its uncompressedshape when delivered into the tympanic membrane. The size and shape ofthe medial flange retention elements are optimal for ensuring that thetympanic membrane pressure equalization tube can be inserted through amyringotomy in a tympanic membrane. The retention elements arelongitudinally aligned with the tubular body lumen and do not overlapone with the other, limiting the cylindrical profile of the tube in thecompressed state, and optimizing recovery to the perpendicular alignmentof the retention elements and the tubular body lumen in the uncompressedstate. Further, the size and shape of the lateral flange retentionelements ensure that the lateral flange is retained on the lateral sideof the tympanic membrane following delivery of the pressure equalizationtube into the tympanic membrane, through the myringotomy.

Another embodiment of a pressure equalization tube 700 according to theinvention includes a cutting tube with sufficient rigidity (i.e.fabricated from a shape memory material such as nitinol or PEEK shapememory polymer) to make a myringotomy when pushed into the tympanicmembrane without the use of additional delivery systems. The tube ispre-shaped with conventional heat/cool methods such that it is normallyclosed prior to use with a sharp cutter edge 702 centered on the medialflange 704 (see FIG. 17). The medial flange, when closed is tapershaped, and will therefore self-dilate when pushed in place. Afterplacement, the tube will be self-anchoring, that is, the medial flange704 will expand as a result of body heat (See FIG. 18). The tube medialflange dilation can be controlled with a cold mandrel inserted into thetube to keep the tube in a closed shape for safe insertion, and thenallow for self-anchoring when the mandrel is removed. For extraction ofthe tube, the cold mandrel can be re-inserted into the tube so that itwill return to its closed shape (as shown in FIG. 17), therebyminimizing the risk of damaging the tympanic membrane from the expandedanchoring flange.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes and substitutions will now occur to those skilled inthe art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that devicesand methods within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. A tympanic membrane pressure equalization tubecomprising: a tubular body with a distal end and a proximal end and alumen therebetween; a medial flange located at the distal end of thetubular body, said medial flange including two or more retentionelements spaced from one another; and a lateral flange located at theproximal end of the tubular body; wherein an outside diameter of themedial flange is greater than an outside diameter of the lateral flange,wherein each retention element is configured to fit within a cylindricalmember of an introducer spaced from the other retention elements, and amaximum length and a maximum width of each retention element is lessthan a circumference of an inner surface of the cylindrical memberdivided by a number of retention elements such that the maximum lengthsand the maximum widths of the retention elements do not allow eachretention element to contact the other retention elements when theretention elements are disposed within the introducer.
 2. The tube ofclaim 1 wherein the outside diameter of the medial flange is betweenabout 3.0 and about 4.0 mm and the outside diameter of the lateralflange is between about 2.0 mm and about 3.0 mm.
 3. The tube of claim 1wherein the medial flange retention elements are of equal size andshape.
 4. The tube of claim 1 wherein the medial flange retentionelements have an uniform width of between about 0.6 mm and 1.0 mm. 5.The tube of claim 4 wherein the medial flange retention elements have anuniform width of about 0.8 mm.
 6. The tube of claim 1 wherein the medialflange retention elements have a length of between about 1.0 mm and 3.0mm.
 7. The tube of claim 6 wherein the medial flange retention elementshave a length of between about 1.8 mm and 1.9 mm.
 8. The tube of claim 1wherein the lateral flange includes at least two retention elements. 9.The tube of claim 8 wherein the lateral flange retention elements are ofequal size and shape.
 10. The tube of claim 8 wherein a width of themedial flange retention elements is equal to a width of the lateralflange retention elements.
 11. The tube of claim 1 wherein the lumen hasa constant diameter.
 12. The tube of claim 1 wherein the lateral flangedefines three notches, the notches circumferentially aligned with thespacing between the three retention elements of the medial flange. 13.The tube of claim 1 further comprising a coating disposed on the tubularbody, the coating configured to reduce adhesion between the medialflange retention elements.
 14. The tube of claim 1, wherein the tube isconfigured to expand from a collapsed state to an uncollapsed statewithin one second.
 15. The tube of claim 1, wherein the tube isconfigured to expand from a collapsed state to an uncollapsed state, andwherein the medial flange retention elements are longitudinally alignedwith the lumen when the tube is in the collapsed state.
 16. The tube ofclaim 1, wherein the outside diameter of the medial flange is betweenabout 2.0 and 5.0 mm and the outside diameter of the lateral flange isbetween about 1.75 mm and 4.0 mm.
 17. The tube of claim 1 wherein theouter diameter of the medial flange is greater than a longitudinallength of the tubular body.
 18. A tympanic membrane pressureequalization tube system comprising: a tympanic membrane pressureequalization tube including: a tubular body with a distal end and aproximal end and a lumen therebetween; a medial flange located at thedistal end of the tubular body and having an outside diameter, saidmedial flange comprising two or more retention elements spaced from oneanother; and a lateral flange located at the proximal end of the tubularbody and having an outside diameter less than the outside diameter ofthe medial flange; and an introducer including a cylindrical member,wherein a maximum length and a maximum width of each retention elementis less than a circumference of an inner surface of the cylindricalmember divided by a number of retention elements such that the maximumlengths and the maximum widths of the retention elements do not alloweach retention element to contact the other retention elements when theretention elements are disposed within the introducer, and eachretention element is configured to fit within the cylindrical memberspaced from the other retention elements.
 19. The system of claim 18wherein the medial flange includes three retention elements.